To enable and to set the combination of a prior mechanical dial-type combination lock are implemented by the mechanical linkage mechanism inside the combination lock. Accurate positioning is required for enabling the combination and setting the combination of such combination lock, particularly, it is more complicated to modify the cipher, in addition to that the lock body is required to disassemble, it is very difficult for the person who have not been trained professionally to complete the operation of setting the code. Furthermore, the amount of the secret keys of said method depends on the amount of the directive wheels inside the mechanical linkage mechanism. In order to obtain a large amount of secret keys, the amount of the directive wheels shall be increased so that the volume and the complexity of the structure will be increased. Therefore, people attempt more and more to use the electronic combination lock, which can be operated conveniently and has a compact structure.
It has been disclosed in the U.S. Pat. No. 6,420,958 an electronic digital lock, it uses a dial coupled to a step motor, when rotating the dial, the signals are generated by the step motor, and are outputted to a microcomputer for counting process via a shaping circuit, and are displayed by a display device. When the rotation of the dial is stopped, the numbers displayed are inputted as a part of the code combination. Since the structure of the step motor is complicated and the price is rather high, and the peripheral circuits, such as the shaping circuit, and the like, are required, therefore the manufacturing cost of such electronic digital lock is relatively high.
Additionally, the input devices of dial-type electronic combination locks have been disclosed in U.S. Pat. No. 4,745,784 and U.S. Pat. No. 4,899,562 respectively, they have the similar structure. The input device of the electronic combination lock comprises a dial, a contact tip which is fixed inside the dial and can be rotated together with the dial, and ten contact points which are distributed as a circle or a half circle corresponding to the moving track of the contact tip and connected to a circuit board. The dial is depressed axially when the dial is rotated to a certain calibration position, and an electrical signal is produced by the contact between the contact tip thereon and a certain contact point corresponding to said calibration position. The electrical signal of each of the contact points corresponds to a different number, and this number is confirmed as an element of the combination.
An input device of the dial-type electronic combination lock has also been disclosed in Japanese Patent P2000-73632. It comprises a conducting sheet fixed on the dial, and two groups of contact points, which contact with the conducting sheet and are distributed intermittently as a circle, and a conducting ring, which is connected electrically with the contact point groups and supplies the power thereto. When rotating the dial, the above two contact point groups are contacted and are turned on intermittently with and by the conducting sheet, and two groups of electrical pulse signals can be obtained from the output leads of the two groups of the contact points. The signals are processed and displayed as the combination elements. In this technical scheme, a confirmation device for confirming the combination code is a button switch installed on the dial.
The electrical signals representing the combination are produced directly by employing the electrical contact method in the above said three kinds of input devices of the electronic combination lock, therefore a problem of the contact reliability may be caused. Particularly, in the input device of the electronic combination lock of the Japanese Patent P2000-73632, there is also the problem of the abrasion due to the contact friction. Furthermore, since the electrical signals representing the combination are inputted directly without isolation, the security protection performance is also insufficient.
Furthermore, most of the prior combination locks are in the form of numeral keyboard, in most of the cases, the keyboard is installed on the panel of the lock body above the handle of the door lock. However, for a handle of combination lock disclosed in U.S. Pat. No. 6,378,344, the numeral keyboard is embedded in the handle of the lock, and the combination is inputted through the keyboard. Since the plane size of the keyboard is large, the volume of the handle is larger than that of a normal handle, thus, it will bring about an uncomfortable feeling when using said handle.
Most of the prior combination locks used for the chests and bags are in the form of mechanical roller, as described above, the structure of the mechanical combination lock is complicated, and it is inconvenient to operate it. For example, for a mechanical combination lock used for the chests and bags as disclosed in the Chinese Patent ZL00261865.6, though it has four digit wheels and employs new structure to simplify the operation for changing the combination, but the disadvantages, such as the amount of the combination keys being small, the mechanical operation for changing the combination being complicated, still exist.